Air-type circuit interrupter



Jan 8, 1957 R. c. DICKlNsoN ETAL 2,777,035

AIRJYPE CIRCUIT INTERRUPTER Original Filed Feb. 25, 1949 2 Sheets-Sheetl Jan- 8, 1957 R. c. DlcKlNsoN ErAL AIMYPE CIRCUIT INTERRUPTER OriginalFiled Feb. 25, 1949 2 Sheets-Sheet 2 '.SQS LIT;

Fig.3.

WITNESSES:

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ENTORS C. 'ckinson 8 ell E. Frink.

United States .Patent i AIR-TYPE CIRCUIT lINTERRUPTER Robert C.Dickinson and Russell E. Frink, Pittsburgh, v

Pa., assiguors to `Westinghouse Electric Corporation, East Pittsburgh,Pa., a corporation of Pennsylvania Original application February 23,1949,-Serial No. 77,794, now Patent No. 2,687,461, dated August 24,1954.

Divided and this application March .30, 1954, Serial v 12 Claims. (Cl.20o-144) This invention relatesto improvements in circuit interrupters,and more particularly to arc-extinguishing structures for circuitinterrupters of the air break type.

This application'is a division of our application 'filed February 23,1949, Serial No. 77,794, now United States -Patent 2,687,461, issuedlAugust 24, 1954, and assigned series of tapered slots formed in spacedplates vof insulatl ing material. Lateral movement of the arc isobtained by a magnetic eld produced by 'a magnetic blowout coil andmagnetic eld poles. This-magnetic eld is also relied upon to produce ablast of unionizedY gas through the arc while the arc is heldsubstantially immovable against the closed ends of the slots in the`plates of insulating material.

It is a general object of the present invention to improve theplateconstruction in an airbreak type of circuit interrupter of the typedisclosed fin the aforesaid patent so Vas to .increase .the velocity ofthe arc ,gases as `they pass upwardly between .the spaced ceramicyplates of the .arc chute structure.

A more specific object is to `provide an improved spacing arrangement of`thespaced plates of a circuit interrupter of the foregoing type.

A more specific object is to improve the interrupting capacity of acircuit interrupter vof the foregoing type Without increasing the.expense `thereof either in regard to assembling operations or in thecost of constructional materials.

Another object is to provide an improved plate convfiguration torestrict .the exhaust passages between tbe plates at the exhaust endofthe arc-chute.

Still a further object -of our invention -is to provide wedge-shaped,spaced plates in a circuit rinterrupter of the air-break type, utilizingeither parallel spacer strips or tapered spacer strips.

Further objects and advantages will readily lbecome apparent upon areading of the following specification taken in conjunction with thedrawings, in which:

Figure 1 is a side elevational view, :partially in vertical section, ofan air break type of circuit interrupter embodying our invention and.shown in the closed circuit position;

Fig. 2 is a. vertical sectional view ltaken on the .line l-l--ll of Fig.1, looking in the direction of vthe arrows;

Fig. 3 is an enlarged plan view of one Vof the arcextinguishing platesformingl .the arc-extinguishing structure; and' Fig. 4A shows a Vsideelevational view of 4the wedgeshaped plate of Fig. 3.

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Referring to the drawings, and more particularly to Fig. l thereof, thereference numeral 1 generally designates suitable contact structurewhich, when separated to the open circuit position, establishes an arcwhich is moved upwardly itno an arc chute, generally designated by thereference numeral 2 as a result of the transverse magnetic field set upby the blowout coil 3 and associated magnet 4structure 4. A rotatablecontact arm 5 carries a conducting bridge 6 which, in the closed circuitposition, as shown in Fig. l, interconnects stationary main contacts 7,8.

A contact stud 9 carries the current from the stationary main contact 7,through an insulating bushing 10 tothe external circuit. The contactstud for the stationary main contact 8 is not shown, but it may beidentical to the contact stud 9.

Consequently, in the closed circuit position of the interrupter, asshown in Fig. l, the electrical circuit comprises the contact stud 9,stationary main contact 7, conducting bridge 6, stationary main contact8, tothe contact stud therefor, not shown, to the external circuit.

During the opening operation of the interruptor, the contact arm 5 isrotated in a clockwise direction about a pivot pin, not shown, but whichisin electrical contact with the stationary main contact 8, to draw anarc between the arcing contacts 11, 12 after the separation ofconducting bridge 6 from the main contacts 7, 8.

When the arcing contacts V11, 12 separate, the arc formed therebetweenwill expand upwardly because of the loop circuit so that one terminalthereof will be transferred to the arc terminal member 1S, and the otherarc terminal will be transferred to the other arc terminal member 19.

When this occurs, the blowout coil 3 will be put into series circuit andthe transverse magnetic -eld set up thereby between the field polemembers 14 (Fig. 2) will move the established `arc upwardly along thearc terminal members 18, 19 into the arc chute 2. The electrical circuitnow comprises contact stud 9, conductor 20, blowout coil 3, contact clip15, arc terminal member 18, the arc itself, arc terminal member 19,llexible shunt 28, contact arm S to the other contact stud, not shown.

The arc chute 2 comprises an insulating rectangularlyshaped housingmember 22 positioned adjacent to an insulating plate 21, the latterserving as a base for the blowout coil 3. Within the housing 22 isplaced a plate 24 composed of an insulating material. Two insulatingspacer strips 25 space a plate 26, composed of an insulating material,away from the plate 24. The plate 26 may have a plurality of apertures27 formed therein which facilitate the venting of arc gasestherethrough, particularly when high currents are to be interrupted. Twomore insulating spacer strips 25 space the plate 26 from a plurality ofplates 29, forming a unitary plate assembly. The plates 29 are composedpreferably of a refractory insulating material, such as a Zirconporcelain, which does not give olf gas when contacting an arc. Theplates 29 have a construction more clearly shown in Figs. 3 and 4 andare separated by pairs of asbestos rope 35.

Above the arc terminal member 19 is a second insulating plate 26, whichis spaced by spacer strips 2S from the right-hand plate 29 of the plateassembly. Two additional spacer strips 25 space the right-hand plate 26from a refractory plate, not shown, which is, in turn, separated fromthe right-hand end of the housing 22 by a plurality of strips of shpaper. Bolts 33a secure the several strips 25, plate 26 and the housing22 to the plate 21. Bolts 34a secure the right-hand plate 26 and itsspacer strips 25 and fish paper strips to the housing 22.

The plates 29 and the spacer strips 35 are cemented together in apreliminary process to form a unitary plate aruosa assembly which may bebodily placed into the rectangular housing 22. Insulating holding strips39 are secured by bolts 38 to the opposed inner sides of the housing 22to prevent the unitary assembly of plates 29 `from being forced upwardlyout of the housing 22 by the pressure of gas formed during theinterrupting operation.

Referring to Fig. 3, which more clearly shows the contiguration of eachinsulating plate 29, it will be observed that each plate 29 has aninwardly extending slot or notch llt) which constricts in lateraldimension in a direction toward the top of the plate 29. Referring towill be observed that the assembling of the plates 29 is such that theupper closed ends of the slots itl are alternately staggered throughoutthe arc chute 2 so that when the arc is forced upwardly into the severalslots itl it will assume a zig-zag contiguration at the upper closedends il of the slots dil prior to its being extinguished.

The opening operation of the interrupter will now be explained. Upon theyclockwise rotation of the contact arm 5, an arc is drawn between thearcing contacts ll, l2 which quickly transfers, because of the loopcircuit, to the arc terminal members 1S, 19 to thereby connect intoseries circuit the blowout coil 3. The magnetic lield set up by theblowout coil 3 between the eld pole members M, sets up a transversemagnetic eld through the arc chute 2, to thereby force the establishedarc upwardly along the arc term' ial members liti, Il@ until it comesinto Contact with the closed ends 41 of the slots or notches 4t)provided in the several plates 29. The magnetic held gives an upwardcomponent of velocity to the electrons which bernhard gas particles andimpart to them an upward velocity. This magnetically produced gas blastcarries ionized gases upwardly to the closed ends il of the slots itiwhere extinction is caused by the magnetically produced upward gasblast, the exhaust gases passing upwardly between the plates 2l* and outor' the arc chute 2. In prior constructions of air break circuitinterrupters of this type, such as set forth in the aforesaid patent, ithas been the practice to position the spacers 35 or sections of asbestosrope parallel to each other at the pposed outer-side edges of each plate29. The spacers 35 constitute a side wall means between adjacent plates29. We have discovered, however, that considerable interruptingimprovement is obtained by placing the spacers or sections of asbestosrope 35 so that a tapered constricted exhaust gas passage i2 is providedbetween each set of adjacent plates 29, as shown more clearly in Fig. 2.in other words, the lateral space A separating the spacers 35 at theupper end of the plate 29 is smaller than the lateral space B separatingthe spacers 35 at the lower end of the plate 29, as shown more `clearlyin Fig. 2.

Thus by drawing the spacers 3S in at the exhaust end ot the interruptingassembly so as to gradually restrict or choke each exhaust passage 42, aconsiderable increase in interrupting ability has been achieved. Theactual reason for this is not known with certainty at present, but thefollowing theory may apply. lt is to be clearly understood, however,that we are not limited or bound by our present theory of the operation,because regardless of any theory proposed, there is a distinctimprovement in interrupting ability achieved. We feel, however, that apossible explanation may reside in the fact that when the arc is at theupper closed ends il of the slots liti, it is at a very hightemperature, and as the gases are travelling upwardly thro-ugh the arc,they pass upwardly to the exhaust end of the arc chtite, in whichpassage they are cooled by the surfaces of the plates 29 and contract involume.

The reduction of the cross-section of the gas path as the gases becomeprogressively cooler maintains the dow at high velocity and increasesthe turbulence and consequently the back pressure maintaining a higherpressure in the interrupting space, and also giving a more uniformmotion of the are in the slot. Even though this proposed theory may beincorrect, nevertheless the fact remains '4 that a substantialimprovement is maintained by the construction set forth in our inventionwithout increase in size, and only a slight increase in assembly labor.

Figs. 3 and 4 show more particularly the wedge-shaped plate 29. Thisplate 29 is wedge-shaped, as shown, and when employed in a stack withparallel spacers 35 will constriet the exhaust passages l2 between eachpair of adjacent plates. Thus, the constricted exhaust passage 4Z may beformed either by wedge-shaped plates alone, with parallel spacers 35, orby wedge-shaped plates 29 with tapered spacers 35, as shown in Fig. 2.

The foregoing description of our invention indicates how we haveincreased the voltage interrupting ability of plate type circuitinterrupters of the type set forth in the aforesaid patent by employingwedge-shaped plates 29, as shown in Figs. 3 and 4. Either parallelspacers 35, or tapered spacers 35, as shown in Fig. 2, may be employedwith the wedge-shaped plates 29. We have set forth what we believe to bethe best theoretical explanation for the phenomena involved but do notlimit ourselves as to the correctness of said explanation. By only asmall or negligible increase of assembly cost, we have improved theoperation of plate type circuit interrupters of the foregoing typewithout increasing their overall dimensions by merely reducing thecross-section of the space between the plates 29 at the exhaust ends ofthe plates.

Although we have shown and described speciic structures, it is to beclearly understood that the same were merely for the purpose ofillustration, and that changes and modifications may readily be madetherein by those skilled in the art without departing from the spiritand scope of the appended claims.

We claim as our invention:

l. A circuit interruptor of the airbreak type including an arc chutecomprising a plurality of spaced wedgeshaped plates of insulatingmaterial, the thickness of each plate increasing in a direction towardthe exhaust end of the arc chute, the plates being so disposed that themedian plane of each plate is parallel to the median plane of everyother plate, means for establishing an arc and moving it against theplates, and the exhaust passages between the plates decreasing incross-sectional area at the exhaust end of the are chute.

2. A circuit interruptor of the airbreak type including an arc chutecomprising a plurality of spaced slotted wedge-shaped plates ofinsulating material, the thickness of each plate increasing in adirection toward the exhaust end of the arc chute, the plates being sodisposed that the median plane ot each plate is parallel to the medianplane of every other plate, means for establishing an arc and moving itinto the slots and against the plates, and the exhaust passages betweenthe plates decreasing in cross-sectional area at the exhaust end of theare chute.

3. A circuit interruptor of the airbreak type including an arc chutecomprising a stack of spaced slightly wedgeshaped plate portions, meansfor establishing an arc, the established arc moving against the slightlywedgeshaped plate portions to effect the extinction thereof, spacingmeans positioning the slightly wedge-shaped plate portions a relativelyshort distance apart which is comparable to the thickness of the plateportions, and the exhaust passages between the slightly wedge-shapedplate portions defined by the slightly wedge-shaped plate portions andby the spacing means becoming smaller toward the exhaust end of the arcchute.

4. A circuit interruptor of the airbreak type including an arc chutecomprising a stack of spaced Wedge-shaped slotted plate portions, meansfor establishing an arc, the established arc moving against thewedge-shaped slotted plate portions to effect the extinction thereof,spacing means positioning the wedge-shaped slotted plate portions arelatively short distance apart which is comparable to the thickness ofthe plate portion, and the exhaust passages between the Wedge-shapedslotted plate portions defined by the wedge-shaped slotted plateportions and by the spacing means becoming smaller toward the exhaustend of the arc chute.

5. A circuit interrupter of the airbreak type including an arc chutecomprising a plurality of spaced wedgeshaped plates of insulatingmaterial, each wedge-shaped plate having a closed-end slot extendinginwardly from one end thereof, a pair of spacer strips separatingadjacent wedge-shaped plates a relatively short distance apart, meansfor establishing an arc and moving it through the slots provided by theseveral wedge-shaped plates, and the lateral distance between each pairof spacer strips diminishing toward the exhaust end of the arc chute.

6. A circuit interrupter of the airbreak type including an arc chutecomprising a plurality of spaced insulating wedge-shaped plate portions,spacing means extending along each side edge of the wedge-shaped plateportions separating adjacent wedge-shaped plate portions a relativelyshort distance apart, means for establishing an arc and moving itsubstantially transversely against the insulating wedge-shaped plateportions to etfect the extinction thereof, and the lateral distancebetween the spacing means along one side edge of the wedge-shaped plateportions and the spacing means along the opposite side edge of thewedge-shaped plate portions progressively diminishing toward the exhaustend of the arc chute.

7. A circuit interrupter of the airbreak type including an arc chutecomprising a plurality of spaced slotted insulating wedge-shaped plateportions, spacing means extending along each side edge of thewedge-shaped plate portions separating adjacent wedge-shaped plateportions a relatively short distance apart, means for establishing anarc and moving it substantially transversely against the wedge-shapedplate portions and into the slots thereof to effect the extinctionthereof, and the lateral distance between the spacing means along oneside edge of the slotted wedge-shaped plate portions and the spacingmeans along the opposite side edge of the slotted wedge-shaped plateportions progressively diminishing towards the exhaust end of the arcchute.

8. A circuit interrupter of the airbreak type including an arc chutecomprising a plurality of spaced insulating wedge-shaped plate portions,side wall means extending along the opposite sides of the arc chute andspacing the wedge-shaped plate portions a relatively short distanceapart, means for establishing an arc and moving it substantiallytransversely against the insulating wedge-shaped plate portions to eiectthe extinction thereof, and the lateral distance between the side wallmeans along one side of the arc chute and the side wall means along theopposite side of the arc chute progressively diminishing toward theexhaust end of the arc chute.

9. A circuit interrupter of the airbreak type including an arc chutecomprising a plurality of spaced insulating wedge-shaped plate portionshaving closed end slots therein, side wall means extending along theopposite sides of the arc chute and spacing the wedge-shaped plateportions a relatively short distance apart, means for establishing anarc and moving it substantially trans versely against the insulatingwedge-shaped plate portions and into the slots thereof to effect theextinction of the arc, and the lateral distance between the side wallmeans along one side of the arc chute and the side wall means along theopposite side of the arc chute progressively diminishing toward theexhaust end of the arc chute.

l0. A circuit interrupter of the airbreak type including an arc chutecomprising a stack of spaced insulating Wedge-shaped plate portions,spacing means positioning the wedge-shaped plate portions a relativelyshort disance apart to dene separate exhaust passages therebetween, themedian plane of each wedge-shaped plate portion being parallel to themedian plane of every other wedge-shaped plate portion so that the endwedge-shaped plate portions of the stack are parallel to each otherthereby obtaining adequate ash-over distance at the exhaust end of thearc chute, means for establishing an arc, means for moving theestablished arc substantially transversely against the wedge-shapedplate portions to eiect the extinction thereof, and the cross-sectionalarea of the exhaust passages through the wedge-shaped plate portionsdefined by the spacing means and by the wedgeshaped plate portionsbecoming progressively smaller toward the exhaust end of the arc chute.

l1. A circuit interrupter of the airbreak type including an arc chutecomprising a stack of spaced insulating wedge-shaped plate portionshaving closed end slots therein, spacing means positioning thewedge-shaped plate portions a relatively short distance apart to defineseparate exhaust passages therebetween, the median plane of eachwedge-shaped plate portion being parallel to the median plane of everyother wedge-shaped plate portion so that the end wedge-shaped plateportions of the stack are parallel to each other thereby obtainingadequate ash-over distance at the exhaust end of the arc chute, meansfor establishing an arc, means for moving the established arc into theslots of the wedge-shaped plate portions substantially transverselyagainst the wedge-shaped plate portions to effect the extinctionthereof, and the cross-sectional area of the exhaust passages throughthe wedgeshaped plate portions defined by the spacing means and by thewedge-shaped plate portions becoming progressively smaller toward theexhaust end of the arc chute.

12. A circuit interrupter of the airbreak type including an arc chutecomprising a plurality of spaced wedgeshaped plates of insulatingmaterial, a pair of spacer strips separating adjacent wedge-shapedplates a relatively short distance apart, means for establishing an arcand moving it substantially transversely against the wedge-shaped platesto effect the extinction thereof, and the lateral distance between eachpair of spacer strips diminishing toward the exhaust end of the arcchute.

Switzerland Sept. l, 1928 Great Britain Nov. 10, 1932

